Electric discharge tube



Dec. 27, 1938. J. L. H. JONKER ELECTRIC DISCHARGE TU-BE Filed FbVze,1937 INVENTOR JO/MNLODEW/JKl/E/VDR/KJONKER ATTORNEY Patented Dec. 27,1938 UNITED STATES PATENT :O'FFIE;

ELECTRIC DISCHARGE TUBE Application February 26, 1937, Serial No.12'7,815 In the Netherlands March 9, 1936 3 Claims.

I The invention relates, to an electric discharge tube, moreparticularly to 'a discharge tube provided with a plurality of grids andto a circuit arrangement comprising such a tube.

It is known to utilize discharge tubes having, for example, four or moregrids, as so-called mixing tubes, for example, in superheterodynereceiving systems. These tubes usually have two grids which are employedas oscillator electrodes for the generation of local oscillations, onegrid which acts as a control grid and if, required, one or two screenswhile in a so-called octode a suppressor grid may be arranged in thetube between one of the screen grids and the anode.

There are various possibilities of distributing the functions among theelectrodes present in the tube. the cathode, may act as generatorelectrodes, the subsequent grid as a screen grid, the fourth grid as acontrol grid while between this grid and the anode there may be locateda screen grid and a suppressor grid. It is also possible, however, toutilize the first grid, reckoning from the cathode, as a control gridand to set up in this case the local oscillations between the third gridand the fourth grid.

Although it is permissible to form all the electrodes located betweenthe anode and the cathode as complete. grids it has been found to bevery advantageous to constitute the anode of the oscillator by only afew preferably rod-shaped parts.

Although with the constructions above-described satisfactory results maybe obtained, there arise in some cases disadvantages which, as has beenfound, may be due to the fact that electrons return from the controlgrid and strike the oscillator anode and thus act upon the frequency ofthe local oscillator.

The invention concerns a device comprising an electric discharge tube,which tube is provided with at least four grids, at least two of thesebeing control grids, which are separated from each other by means of oneor more positive electrodes while one control grid completely surroundsthe cathode and an electrode, consisting of only a few, preferablyrod-shaped parts. Owing to this, electrons issuing from one of thefollowing grids can no longer reach the above mentioned electrodeconsisting of rod-shaped parts while notwithstanding the second gridcannot be struck by elec trons coming from the cathode. Owing to thisthe tube according to the invention may be employed with great advantageas a mixing tube in superheterodyne receiving systems in which thesegrids, which are located in closest proximity with Thus, the first twogrids, reckoning from 1 the cathode, that is to say the electrode whichconsists of rods and the grid which surrounds said electrode, act asgenerator electrodes, that is to say as the anode and the gridrespectively of the generator.

It has been found to be advantageous to construct the second grid,reckoning from the cathode, in such manner that those portions which arelocated in the neighbourhood of the rod-like portions of the first griddo not consist of grid shaped material but consists, for example, ofgrids bent so as to take the shape desired. I

As set out hereinbefore, a discharge tube according to the invention maybe employed in superheterodyne receiving systems. According to oneparticular embodiment of the invention, the tube comprises at least fivegrids of whichthe third grid and the fifth grid are connected to oneanother. According to another form of construction there may beprovided, in addition, a sixth grid which is connected inside the tubeto the cathode.

It has previously been proposed to mount the anode of the localoscillator in closer proximity to the cathode. In this case the anodeconstituted the third grid, reckoning from the cathode, so that therewas not any question of the effect aimed at with the constructionaccording to the present application.

The invention will be explained more fully by referring to theaccompanying drawing which shows diagrammatically, by way of example,the arrangement of the electrodes of an electric dis charge tubeaccording to the present invention.

In the drawing I denotes the cathode of a discharge tube. In closeproximity with this cathode are arranged two rods 2 which form auxiliaryanodes, the cathode and said auxiliary anode being completely surroundedby a grid 3. This grid consists of a grid-shaped portion 4 and at bothends that is to say at the points located nearest to the rods 2, of twoscreens 5, The tube further cornprises grids 6, 1, 8 and 9 and an outputanode Hi. As is diagrammatically shown in the drawing, the grid 9 isconnected to the cathode while the grids B and 8 are connected to oneanother. If the tube is employed as a mixing tube in a superheterodynereceiving system, the first grid and auxiliary anodes may be utilized asgenerator electrodes, the second and the fourth grid as screen grids,the third grid as a control grid and the fifth grid as a suppressorgrid. It would, however, also be very well possible to utilize such atube in another manner, for example as a triode-hexode.

What I claim is:--

1. An electron discharge device having a cathode, an auxiliary anodeadjacent said cathode, a control electrode surrounding said cathode andanode, a screen electrode, a second control electrode and an outputanode, said first control grid being provided with a solid sheet metalshield for shielding said auxiliary anode from all the electrodes butsaid cathode and first control electrode.

2. An electron discharge device having a cathode, a pair of auxiliaryanodes disposed on opposite sides of said cathode, a control gridsurrounding said cathode and auxiliary anodes, a screen grid, a secondcontrol grid and an output anode, said first control grid being providedwith solid sheet metal shields adjacent and partially surrounding theauxiliary anode for shielding said auxiliary anodes from all of theelectrodes but said cathode and first control grid.

3. An electron discharge device having a cathode, a pair of auxiliaryanodes disposed on opposite sides of said cathode, a control gridprovided with oppositely disposed side rods adjacent said auxiliaryanodes and surrounding said cathode and auxiliary anodes, a screen grid,a second control grid and an anode, and U-shaped solid sheet metalshields secured to said side rods and shielding said auxiliary anodesfrom all of said electrodes except said cathode and first control grid.

J OHAN LODEWIJK HENDRIK J ONKER

